Phase transition and enhanced multiferroic properties of (Sm, Mn and Cr) co-doped BiFeO₃ thin films

Pure BiFeO₃ (BFO) and (Sm, Mn, Cr) co-doped Bi _0.89Sm_0.11Fe_0.94Mn_0.04Cr _0.02O₃ (BSFMCO) thin films were prepared on FTO/glass (SnO₂:F) substrates via a sol-gel method. Structures of BFO and BSFMCO thin films were investigated by X-ray diffraction (XRD), Rietveld refinement of XRD patterns and Raman scattering spectra. The results indicated a phase transition from trigonal (R3c:H) BFO thin film to tetragonal (P4) BSFMCO thin film. The BSFMCO thin film exhibited enhanced multiferroic properties compared to the BFO thin film. The improved remnant polarization (2P _r=109.95 μC/cm²) and saturated magnetization (Ms=1.22 emu/cm³) have been observed in the BSFMCO thin film. At an applied electric field of 150 kV/cm, the leakage current density of the BSFMCO thin film is 1.58×10^-6 A/cm², which is about three orders of magnitude lower than that of the BFO thin film (1.25×10^-3 A/cm²).